Telephone-exchange system



2 Sheets-Sheet E. W. HANCOCK TELEPHONE EXCHANGE SYSTEM Filed March 21.

Aug. 7, 11923.

Aug. 71,1923.

E. W. HANCOCK TELEPHONE EXCHANGE SYSTEM Filed March Patented Aug. 7, 1923.

n iren sr ares PATENT OFFICE.

EDMUND W. HANCOCK, OF NEW YORK, N. Y., ASSIGNOR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXOHANGE SYSTEM.

Application filed March 21, 1921. Serial No. 454,105.

T 0 all whom it may concern Be it known that I, EDMUND W. HANCOCK, a citizen of the United States of America, residing at New York, in the county of New York, State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems and more especially to systems in which connections extending through a plurality of oflices are established by means of machine switching apparatus located in the different offices involved.

In certain types of interoflice exchange systems calls which are destined for outlying districts are first received at the originating oflice by an answering operator. The operator is provided with central ofiice register senders and a keyboard at her position. After orally receiving from the call ing subscriber the destinationof the desired line she makes a record thereof on the keyboard which causes the register sender to take a corresponding setting. With the record of the called line established on the register sender of the originating ofiice it then becomes effective to control automatic switches to select an outgoing trunk line leading to the proper distant mechanical office. At the distant ofiice the incoming trunks extend to automatic selective switches. In order to control the selective operation of the automatic switches in the distant office, register sender' are provided thereat similar in function to those at the originating oflice, except that in the latter case the senders are positioned by means other than an operators keyboard. I

When an interoflice trunk has been se lected an idle one of the register senders at the distant ofiice is associated with said trunk. Following this the record of the desired designation, which was first estabward its destination.

here the originating office concerned in an interofiice connection is full-mechanical in character the calling subscriber causes the setting of the register sender thereinby means of an impulse transmitter. The switches at the originating oflice are operated to select an outgoing trunk, the record is transferred to the distant office sender and the switches of the distant offices are operated in the same manner as above outlined.

Inasmuch as the number of register senders, provided at the distant or tandem office for serving the trunks incoming from an originating office, must necessarily be limited it may frequently occur that all of these senders will be simultaneously busy. lVith all senders busy a connection extended over one of the interofiice trunks to the distant oiiice would receive no attention,

since there is no sender available to take the transferred record and to control the further establishment of the connection Consequently, while there may be idle trunks at the time in the interoflice group, the selection of one of these trunks by the switches at the originating ofiice is of no avail owing to the fact that the busy condition of all senders at the distant oflice prohibits the further extension of the call.

lVith the foregoing facts in mind, the object of the present invention is the provision of means controlled jointly by the register senders in the second office for rendering all trunks of the group incoming from the first ofiice non-selectable at the first office A feature of the invention relates to the provision of a plurality of groups of senders serving respectively a plurality of groups of interoffice trunks, and a common group of senders serving all trunks, together with means whereby all trunks of any group are rendered non-selectable at their outgoing end when all senders individual to that group and all of the common senders at the incoming end of said trunks are simultaneously busy,

Such other and further features as are contemplated by the present invention will become more clearly understood from a consideration of the following description and the appended claims.

Figs. 1 and 2 of the drawing when taken in order illustrate an interoflice telephone system wherein the subject matter involving the principles of the invention is shown: in sufficient detall to enable athorough con1 prehension thereof. Fig. 1 shows a' first or originatingoflice, with one ofthesubscribefls v 5 lines terminating therein before an operators position and an operators cord circuit, one

end of which terminates in a plug andthe. other end in the movable brushes of a selec tor switch. This figure also illustrates a Qplurality of trunk lines accessible to the selector switchwhich lead to a distant oflice. Furthermore this ,figure illustrates equipment wherebythe outgoing trunklines may .be rendered non-selectable to the selector switches such as the one shown. Fig. 2illusgrammatic mannerv a plurality of register I ltrates a, distant oflice at which the interoliice trunks incoming from the originating joflice .termiiiate in the movable brushes ofselector switches. f This figure also discloses in a diaiTo avoid the unnecessary details in the showing. of. the selector switches, the register sender. and ,the operators equipment at the originating office in 1, these various ,e'lernents have been illustrated in schematic .-form." iThe selector switch, known as the ,district selector, is, of the well-known powerdriven panel type suchf as the switch shown and described in detail in the patent to Craft and Reynolds 1,123,696, issued J anuary, 5, 1915. This switch consists of a verti- ,.cal brush shaft 110 carrying a plurality of ,sets of brushes, two of which are shown at 111 and 112. All of the brushes carried on .the shaft; 110 a re connected inmul'tiple to the, operatorscord .circuit,the other end of inserted in thejack 101 of a calling subscribers line.

drive magnet 108 is arranged to press the depending ,portionof said shaft against the [constantly rotating drum 131. The clowndrive -powerinagnet 132, when energized, ,,presses thedepending portion of said shaft '1 against a drum 133 rotating constantly in the,..op.posite direction. to cause the down 1 ward or restoring movement of the switch.

The register sender schemationl ly shown within the dotted rectangle 105, a plurality of which are provided at the operators position, serves as a medium for receiving the ,record, of the desired dest nation and to control inaccordance with this record the move- Fig. 1,toselect a trunk leadingto the desired distant office in the case of an inter .oflicecall and also to exercise the necessary 5 p Th first part consists of relays 121, 123,

. control of the apparatus beyond to properly direct a'further establishment of the connection. This sender comprises a plurality ,conductors 120,137,138 andf139 terminate which terminates in the plug 102 adapted to ment of the district selector switch shown in of,registers, .anoperators keyboard and the other usual elements. Inthe schematic illustration, however, only the stepping relay 106 included in the ,fnn damental' circuit ,and one of the counting relays 1 07,- are-gshown.

The sequence switch 103, which is of the usual type,-serves by means of its several contacts (not shown) to control the necessary change-over" functions involved in the operation of the district selector.

The terminal bank of the selector switch is divided into a plurality of groups,o ne for eachof the several sets of .brnshes'carried on-theshaft'llO. :Two of these. groups :113

and 114 are. shown. The group llt consists of the terminals of a plurality of 'tru'nk'lines outgoing tothe distant ofiicershown iiriFig. 2. One ofthese trunks 115, 116 and 117 is shown completely, the talking conductors 115 and 116thereof extending to the'distant office andthere terminating in'the bru'shes of theselector switch 200'. 'The third or test conductor 117 terminates in the contact of The terminals r three other relay 126. trunks are shown for the group 11 1', thetest' conductors 134,135 and -136 of these three trunks terminatingin the contacts ofrelays 126 and 125. A lthoughnot shown, it is understood, of course, that any number of trunks l desirable may be; included in the group 11 1 and that these trunkslead to the distant olfice andjterminatein the brushes of selector switches similar to switch 200 i In a ,similar ,manner theigroup' 113 is.

shown as consisting of the terminals of four trunklines, one of; which, 118, 119, extends to the distant foflice and terminates in the brushes20l of a selector switch. The test in the contact of rel ays 129 and 128." larly, the group 1 l3l may comprise as; many trunks asf desired. Also the other trunk roups servedb 7 brush sets not shown 5 For propelling the brush shaft 110 anup-" y may have talking conductors leading to the distant office andtest conductors which I terminate in the contactsiofrelays 125,126, 127, 12 8, 129 andfieo.

groups For example, a certain number of brush groups, onejjof which, is the brush group 114, may .comprise the first major group. of outgoing trunks. jThe second/ majorf group then will. consist of the remaining brush-groups ofwhich the brushlgroup 113 v is, one. The, make busy equipment shown, in the lower right hand{,corner of Fig. 1 is accordingly divided into twoparts.

125, 126, and 127 individual to 'the -first major group of outgoing trunks and serves n ce under the proper conditions to render said trunks non-selectable to the district switches The second part of the make busy equipment consisting of the relays 122, 124, 128, 129 and 130 is individual to the second major group of outgoing trunks for an identical purpose.

Inasmuch as only two interofiice trunks 115, 116 and 118, 119 are fully shown, only the two corresponding selector switches 200 and 201 in the second ofiice are illustrated. It is understood, of course, that for each of the other incoming trunk lines there is provided an individual selector switch similar to switches 200 and 201. Each selector switch at the distant ofiice has an individual sender selector which serves to associate its incoming trunk with an idle one of a plurality of register senders. The sender selector individual to the trunk 115, 116 of the selector switch 200 is illustrated by the brushes 202, 203 and 204. The brushes of the sender selector switch have access through their terminals to a group of register senders which serve the first major group of interoflice trunk including trunk 115, 116. The three register senders 210, 215 and 220 shown within the small broken rectangles at the right of Fig. 2 belong to the group of senders which normally serve the first major group of incoming trunks. Obviously, there may be as many senders in this group as the traffic requirements justify.

The sender selector switch which is individual to the interoflice trunk 118, 119 and the selector switch 201 is represented by the brushes 205, 206 and 207. These brushes have access through their terminals to a second group of register senders which are individual to the second major group of interoflice trunks containing the trunk 118, 119. Likewise, only three of the register senders 225, 230 and 235 in this second group are illustrated. Each of the incoming trunks of the first major group is provided with a sender selector switch having brushes similar to brushes 202, 203 and 204 which have access to terminals connected in multiple to the conductors shown leading to the register senders 210, 215 and 220 of the first group, that is to say, all of the sender selectors associated with the first major group of incoming trunks have their terminals connected in multiple, whereby anyone may select any idle register sender of the first group of senders. The same is true as regards the register sender provided for the incoming trunks of the second major group, whereby any one of these may select any idle sender in the second group of senders.

In addition to the two groups of individual senders already described there is provided a third or common group of register senders at the distant oiiice, two of which are shown at 240 and 245. The senders of this third group are arranged in common to both the major groups of incoming trunks and may be chosen by the sender selector switches associated with the trunks of either incoming group. For this purpose the conductors which lead to the various elements of the register senders 240 and 245 are multipled to the corresponding terminals in the sender selector switches associated with both groups of incoming trunks.

It has not been considered necessary to show in detail the complicated structure of the register senders. illustrated by a few out its characteristic ele ments. For example, the sequence switches 211, 216, 221, 226, 231, 236, 241 and 246 are individual respectively tothe several senders and serve the well-known purpose of controlling their operations. Relays 212, 217, 222,227, 232, 237, 242 and 247 are the respective stepping relays included in the fundamental switch controlling circuits. Relays 21s, 21s, 22s, ass, 243 and 248 are the well-known O counting relays oi the respective senders which serve to sever the fundan'iental circuit at the completion of each selective movement of the switch and of succeeding switches (not shown). The purpose of relays 214, 219, 224, etc, one of which is provided for each register sender, will become apparent from the following description.

The selector switches diagran'imatically illustrated at 200 and 201 are also switches of the power-driven panel type such. as shown in the patent to Craft and Reynolds 1,123,696, issued January 5, 1915. For a complete description of the detailed construction and operation 01 the selector switches. register senders and other circuits represented, in Figs. 1 and 2 of this disclosure, reference is made to the patent to E. 1V. Hancock, No. 1,439,785, granted December 26, 1922.

When the calling subscriber of line such its line 100 initiates a call. a line lamp (not shown) is lighted before the operator in the central ofiice. In response to the signal the operator inserts the plug 102 of an idle cord circuit in the jack 101 of the calling line. In the manner described in the above mentioned application the insertion of the plug in the jack auton'iatically causes an idle register sender 105 to be associated with. the

.cord c rcuit and also causes the operators Instead, each sender iii of the several sets of brushes and then to drive the selected set of brushes ov er the terminals of the group to which it has access to choose an idle trunlroutgoing to the desired distant ollice. It will be assumed first that the brush set 111 is chosen which has access to the first major group of outgoing trunks. It will further beassunied that some oneo'l' the register senders 210, 215 and 220 of the group of senders in the distant ollice in lividual to the first major group of interoflice trunks is idle at the time. Following the selection by brushes 111 of an outgoing trunk in the first major group, such as trunl-I: 115, 116, the sender selector switch, 202, 203, 204 individual to trunk 115, 116 is set in operation to select an idle register sender. it

end set of terminals 254, 255 and this sender is seized and associated with the incoming trunk 115, 116.

The record originally registered y means of the operators keyboard at the sender in the originating oflice may now be trans ferred over the trunk 115, 116 and reproduced on the registers (not shown) of the selected idle register sender 215 in the distant otlice. The record having thus been transferred the sender 215 becomes effective to control, over its fundamental circuit, the selector switch 200 and succeeding switch to ertend the connection to its dest nation. During the period that the sender 215 is engaged, a ground potential is extended from the selector switch 200 as by means of a re lay 250, over the brush 202 of the sender sclector, terminal 254, conductor 25?, winding of relay 219 to battery and ground. Relay 219 is energized and serves thereby to indi-' cate that the register sender is busy.

Should all of the register senders of the group individual to the first major group of interofiice trunks be busy when a connection is extended to the distant office by way of one of said trunks, such as trunk 115, 116, then the brushes 202,203 and 204 of the sender selector are advanced to test the ter minals representing the senders 240, 245, etc., of the common group of senders. Provided the first of these, sender 240, is idle, the brushes 202, 203 and 204 stop on the terminals 258, 259 and 260 and the sender 240 is seized and associated with the trunk 115, 116. After the conversation has been completed the connection may be restored in any well-known manner.

Had the district selector switch in the orig;

inating office been operated to choose its brush set 112 which has access to the trunks of groups 113, the connection would then be extended over an interotlice trunk of the second major group, such as trunk 118, 119, which terminates in the brushes of the switch 201 at the distant office. In this case the sender selector switch 205, 206 and 20'? is set in operation to test the condition of the register senders 225, 230 and 235 of the second group of senders individual to the second major group of interoffice trunks. If idle, one of these senders is seized and associated with the incoming trunk for the same purpose already explained. If, how ever, none of these senders is idle at the time, the sender selector switch 205, 206, 207 searches for an idle sender in the common group: a

It will now be considered that the establ-ishment of a connection is attempted over the first major group of trunks 114 at a time when all of the register senders 210, 215 and 220 individual thereto and also all of the common senders 240 and 245 are busy. Since all senders available to any of the trunks in the first major group are simultaneously busy, it would be useless'for the district selector switch to 'seize oneof these trunks and extend the connection to the distant ofiice. Consequently, this unnecessary operation is avoided in a manner about to be discussed. Inasmuch as all of the senders 210, 215, 220, 240 and 245 are simultaneously busy, their individual relays 214, 219, 224, 244, 249 are energized. A circuit is therefore established from battery through the windingof relay 208, armatures and contacts of relays 214, 219, 224, 244' and 249 in series to ground. Relay 208 energizing in this circuit establishes a circuit from battery through its armature and contact, conductor leading to the originating office, thence through the winding of relay 121 to ground. Relay 121 completes a circuit at its armature and contact for relay 123. Relay 123 at its arma'tures and contacts closes circuits for the relays 125, 126 and 127. Relays 125, 126 and 127 become energized and apply ground potential to the test terminals of all trunks in the first major group by way of conductors 117, 134, 135 and 136. Hence, when the district selector switch 110 is operated to drive its brush set 111 over the terminals of the group 114, all of these terminals will be found artificially busy, and the connection will progress no further.

In a similar manner if a connection is attempted by way of the second major group of oflice trunks 113 at a time when all of the senders servin g such second major group together with all of the common senders are busy, the trunks of this group are found-nonseleotable and the establishment of the connection is arrested. Since the senders 225, 230, 235, 240 and 245 are simultaneously busy, their relays 229, 234, 239, etc. are operated and a circuit is closed from battery through the winding of relay 209, armatures and contacts of relays 229, 234, 239, 244 and 249 to ground. Relay 209 is operated and completes a circuit from battery through its armature and contact, conductor 253 leading to the originating ofiice, through the winding of relay 122 to ground. Relay 122 operates and completes a circuit for relay 124. Relay 124 at its armatures and contacts closes circuits for relays 128, 129 and 130. These relays are energized and apply ground potential over conductors 120, 137, 138 and 139 to the test terminals of all trunks in the second major group 113. Consequently, when the district selector switch 110 is operated, it will find its trunks non-selectable, and further extension of the attempted connection will be prohibited.

So long as all register senders of either individual group at the distant office together with all senders of the'common group remain busy, the corresponding group of interofiice trunk lines are held non-selectable,

as above explained, to the district switches in tential from the interoflice cable conductor" 252 permitting relay 121 the originating oflice to retract its armature. Relay 121 opens the circuit of relay 123, which in turn, breaks the circuits of relays 125, 126, 127, etc. These relays all retract their armatures simultaneously and remove the artificial busy condition from the trunks of the first major group 114, whereby the district selector switches may select any trunk in such group which is not busy by reason of a previously established connection.

Although the invention has been illustrated in this disclosure as embodied in a semi-automatic system involving the use of operators equipment, it should be understood that no such limitation is necessary. The trunk groups, which are rendered busy under certain conditionsto avoid the useless extension of connections, may as wellbe selected by full automatic apparatus controlled directly trom the calling subscrihers substation. Moreover, it is not essential to the principle of the invention that the same be shown in connection with the intero'llice trunk groups. It is applicable to trunk groups interconnecting successive switching stages of one and the same central ofiice.

What is claimed is:

1. In a telephone system, a trunk line, switching means for selecting said trunk to extend a connection thereover, a second switching means for further extending said connection, a plurality of register senders for controlling said second switching means, and means for rendering said trunk non-selectable to said first switching means when all of the register senders are simultaneously busy.

2. In a telephone system, a trunk line,

switching means for selecting said trunk to extend a 1 connection thereover, a second switching means for further extending said connectiom'aplurality of register senders switching means-for further extending said connection, a plurality of register senders for controlling said second switching means,

means for associating an idle one of the register senders with said trunln and means for rendering said trunk non-selectable tosaid first switching means when all of the register senders are simultaneously busy.

4. In a telephone system, a group of trunks, automatic switches, switching means for extending connections over said trunks to the automatic switches, a pluralityof regisi ter senders for controlling the automatic I switches to turther extend said connections, means for associating the register senders with sald trunks, and means for rendering the "trunks of said group non-selectable to said switching means when all of said register senders are simultaneously busy.

5. In a telephone system, a group of trunks, automatic switches, switching means for extending connections over said trunks to the automatic switches, a plurality of register senders for controlling the automatic switches to further extend said connections, means individual to each trunk for associating an idle register sender with such trunks, and means for rendering the trunksof said group non-selectable to said switching means when all of said register senders are simultaneously busy.

6. In a telephone system, a plurality of automatic switches, a group of trunks each of which leads to one of said switches, switching means for selecting said trunks to extend connections to said automatic switches, a plurality of register senders for controlling the automatic switches to further extend said connections, means for asforextending-iconnectio ns over said trunks: to" the. automatic switches,- a plurality of register sendersforfcontrollingvthe' automatic sWitchesto further extend said con nect'ions; meansnfor iLSSOClEt'UIlI llhB register--- senders with sa1d trunks, means lncludingan-element-in each of said senders fOI'mClOS" mg" a EllCllalllWllBIl all of said senders are simultaneously- .busy, and means responsive 'to 'the closure-of such circuit for rendering thewtrunks 'of said groupunon-seleetable to said switching-means;

8.111 a telephone system; a group of trunksyautomatic switches switching means i for extendin lconrn'ections' over said trunks to the "filltOIlltLtlG SWltCl'lQSg-it first and a'second group of regggister senders for controlling the automatic. switches to further extend said connections, means :for associating a reg1s-- 'ter sender :-of theyfirst "group "when *one of such: senders is idle and: for associating a registen'sender of the second group when all sendersof saidfirstlgroupare busy with said trunksytand means: for rendering the trunks 1 of said =tru'nk group non-selectable to i Sitld switching: 1means==When all register senders of both groups of'register' senders "are simultaneously busy;

9. Ina =telephonewsystem,-a plurality:- of

groups of-*trun-ks,-

automatic switches; switchingmeans for extending connections over said trunks to the automatic switches,

a plurality 'ofgroups f register sender's; one -foreach' "group :of trunks; a group of- 'register sender's commonto all :groups of trunksr said 5 sendersservin'g to control the l v groups automatic-switches to furtherextend said connections," and means operative "when allsenders of-any group together with all send ers ofsaid common group are simultaneous responding groupof trunks non-selectable to said switching meansfi 10. In a telephone system, a plurality of of trunks, automatic switches, switching means for extending connections over saidtrunks to theautomatic switches,- a plurality of groups of register senders, one'for'each group of trunks, a group of reg1S.-'

ter senders common to all groups of trunks,

said senders serving to control the-automatic switches to further extend said connections,

means for associating saidsenders with said trunks, and means operative when' 'all sendersofany group together Wltlr all senders spondinggroup of trunks non-selectable to said switching means.

11. In a telephone system, a trunk line,

for further extending saidconnection, a

EDMUND W. HANCOCK.

40 ly busy for rendering the trunks of the cor-- ofsaid commongroup are 'simultaneously "busy for renderingthetrunks of the corre' a switch for selecting said trunk to 6X\ tenda connection thereover a second SWltCll' 

